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Zone(s) stuck open, replaced valves - no luck. Now what?

I have a 6-zone system. When I started up this spring, zone 6 would not shut off. Opened valve, cleaned out, reassembled. Worked fine for one or two cycles, then same problem. Then zone 1 began to exhibit same problem. System is 13 years old, so I got 2 new Rainbird 100DV valves and replaced them. Surprised and a little irritated to find I still have the same problem.

I'm thinking this must now be either a controller issue or a short somewhere in the system. Any thoughts for troubleshooting would be appreciated.

its to late to explain everything. look around these posts a few of us pros have gone into detail like last week on how to do this. a quick run through though
go to valve box when valve is stuck on and running, turn each valve on, when the stuck zone is running and you turn another valve on,the pressure will drop on the stuck zone, so with the zone stuck on,open another valve,if the pressure drops on the stuck one,thats not the valve. do this until when you turn a valve on, the pressure increases or stays the same. this is for sure 1 of if not the stuck zone. if this is happening often,there is probably debris in the valve,it just moves and shifts causeing it to stick. open valve up shine a light in there since the rainbird valve is black and you can not see some things in it. turn the water on for like 2 seconds while its all apart,make sure you clear all around the valves so the water doesnt lift crap into the valve when it cant go anywhere. make sure you look with the light first,its always good to know whats causing the problem rather than just fix it. then the next time you will know what to do.
if its a clock issue, when the valve is stuck on. unplug it,or shut it off. if its an electric issue the valve will shut right off. if it doesnt. its debris moving from one valve to the next,or you dont have the right valve out there that youve been replacing. make sure everything is clean and in good shape on the valves. you can also feel the solenoid to tell if it is receiving power.
take a look around there is alot of info and tips on stuck valves.
looks like i went a little bit more than a quick run through lol

Zone(s) stuck open, replaced valves - no luck. Now what?

Thanks for the ideas. I did replace what were believed to be the offending valves, so I know they're not stuck open. My system has a main trunk, with 6 valves in individual boxes as the trunk goes down the lawn.

The valves in zones 1 & 6 are stuck open. After replacing those two valves (which didn't change anything), I tried switching the wires at the controller for zones 5 & 6. Then turned on zone 1, and zone 6 was still open (although it was now connected to zone 5 at the controller). So I feel somewhat confident the problem is not the controller or the valves. I'm thinking that only leaves the wires between the controller and the valves. My latest guess is a short or exposed wire somewhere on the route, possibly exposed wires for zones 1 & 6 touching each other. Am I on the right track?

If zones 1 and 6 are some connected then they should both shut off when you switch to zone 2. To take the electrical part out of the picture unhook the wires to the solenoids to valve 6 if it still runs with zone 1 then its not electrical and should be cleaned as suggested earlier or replaced again. Before doing both confirm that it is actually the correct valve for zone 6. I would open the bleed screws individually on the valves to determine which ones went with which zones. This will work if you don't have a master valve or pump start. If you have those you will have to start the system to supply water tot he main line. Service techs method will work on finding the valves.